WSM Piston/ Top end HELP!!

Pwgsx

Go big or go home
Location
DFW-Texas
I need help.....I got a set of wsm pistons for a top end on my engine. This is stock bore size as I got a new oem cylinders. When looking at the bottom of the old piston and the new, the old one has more material cut out on one side than the wsm new pistons (see pic). Is this ok ??

Also it says to install the C-clips in the "up" position?? I dont know bc all I got was 2 small wire rings, how do I make sure they are facing up??Does this matter??

How do you get them in and the old ones out?? They are in there pretty tight!!!!

And lastly, What is easier, installing the pistons thru the top and then connecting everything up from the bottom or installing the pistons on the rods/bottom end first and then putting them in from the bottom one at a time??

thanks guys, this is my first engine job.
 

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Motorheads5

Livin the generation gap
Location
ketchikan alaska
That's good you have given this some thought lol I have done it both way's depending whether you have side shim's to install on the con rod bearing's or not if not then install the piston's in the bore and then install wrist pin's one at a time I have had good luck doing it this way . Just my opinion K
 

Waternut

Customizing addict
Location
Macon, GA
I believe the sides of the piston are cut out more on the new piston because it helps cool the pistons better that way.

The c clips don't have to be installed in the up position but the end of the clip shouldn't be too close to the notch for your pliers on the piston.

I've never installed the pistons in the bore before putting them on the crank. I guess if you have some help, either way is fine. I've always attached them to the crank and lowered the cylinder around them...even by myself but I'll admit, it's a pain. I'm sure both ways have their ups and downs.
 

Pwgsx

Go big or go home
Location
DFW-Texas
Make sure the wrist pins are the same size. Your new pistons have bigpin style skirt.

Now im confused, I took the wrist pin out of the old piston and its the exact same size as the wrist pin on the new piston, I fit it in and everything. So it cant be that!!!

Any other ideas or is the way the piston skirt is cut on the new set ok to use?? It just looks way different which is why im concerned!!
 

the WaTeRhAwK

fryin' up a/m electrics..
Location
okc
c-clips are stamped. so being in the "up" position means the sharp edged side of the clip faces out, the rounded edge faces inward. if you're using the wire clips, then it doesn't matter. getting the c-clips out usually requires a c-clip removal too, that is reversable, meaning you can make it either close together or open apart by switching the pivot screw out. they look like a strange pair of pliers with tips that go into the holes of the clip. as far as removing wire clips, I just use a sharp screwdriver that's been turned down on a grinder to resemble an awl, or just use an awl. stuff a rag down into the cases around the rods so if you loose hold of the clip it doesn't fall down into the cases. going to the trouble to disassemble a set of cases just to retrieve a small wire clip can put you in a really bad mood...lol
 
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Pwgsx

Go big or go home
Location
DFW-Texas
its a 04 750sx- small pin

ok got the c clips and everything together. The top case is a oem replacement so no boring or anyhting has been done to it. The pistons are 80mm oem size to fit the oem top case. But am still wondering why the new pistons looks so much different than the oem piston i removed as seen in the pics???
 

Waternut

Customizing addict
Location
Macon, GA
its a 04 750sx- small pin

ok got the c clips and everything together. The top case is a oem replacement so no boring or anyhting has been done to it. The pistons are 80mm oem size to fit the oem top case. But am still wondering why the new pistons looks so much different than the oem piston i removed as seen in the pics???

Are you positive it's a small pin? Unless you or someone else swapped the engine, an '04 750 would have the big pin motor.

Just because it's stock size, doesn't mean that a different manufacturer will create an identical piston as the OEM. They could actually get in trouble that way.

An OEM pipe is different from a Coffman pipe which is different from a Factory pipe which is different from a Protec pipe... The all perform the same function on the same engine but because of different designs, they all perform differently.
 
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Pwgsx

Go big or go home
Location
DFW-Texas
im sorry, i meant a 94, it should be a small pin for sure. So the piston "look" should be ok with fitting and working with my engine just fine??
 
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